MORE than 50 years after they were executed as Soviet spies, the case of Julius and Ethel Rosenberg continues to generate intense emotion on both sides of the political spectrum.

For the left, it has long been an article of faith that two wholly innocent radicals were framed and executed solely because of their politics.

Now, the couple’s granddaughter, Ivy Meeropol, has made a documentary that largely reinforces that viewpoint.

“Heir to an Execution,” which premieres Monday on HBO, is a portrait of two people so filled with love and warmth they couldn’t possibly have betrayed their country.

This is an often-compelling film. It plays to the viewer’s emotions, and there are some powerful moments, such as when Ivy’s father and uncle, Michael and Robert Meeropol (they took their adoptive parents’ name), return for the first time to the Knickerbocker Village apartment in which they watched their father being arrested in 1950.

Ivy Meeropol uses images of classic liberal villains from the ’50s – Joe McCarthy, Richard Nixon and J. Edgar Hoover – to reinforce what she sees as the nefarious nature of those who opposed her grandparents.

And in what is meant to be the film’s dramatic highlight, she takes a drive past the home of Ethel’s brother, David Greenglass – the prosecution’s star witness.

It’s clear from the outset that this isn’t meant to be an honest or objective look at the Rosenberg case. Which is why so little of the film is devoted to the avalanche of previously secret documents – from both U.S. and Soviet sources – released in the past decade that overwhelmingly confirm Julius Rosenberg’s role as a major spy for the USSR.

Even when the new disclosures are addressed, it’s in a way that casts doubt on their truthfulness.

“A reasonable case can be made that Julius Rosenberg, with Ethel Rosenberg’s knowledge, was involved in military and industrial espionage,” says Robert Meeropol. “But a reasonable case can also be made that this is all government- manufactured disinformation.”

Even hinting that their parents might have been spies is a dramatic about-face for the Meeropols. Which is no doubt why they offer tortured excuses to explain why Julius and Ethel continued to maintain their innocence.

“They weren’t guilty of what they were charged with,” namely stealing the atom bomb, says Michael Meeropol. “That’s why they said they were innocent.”

Indeed, while the brothers now admit that the Venona files – decrypts of intercepted Soviet cables – suggest that Julius “did stuff,” they also insist that their parents “were framed.”

In her effort to portray her grandparents as loving people, there is no discussion whatsoever about their ideological zealotry; indeed, the C-word – communism – is hardly mentioned.

But it was that fanaticism that allowed the Rosenbergs to voluntarily choose martyrdom, leaving their two young sons behind as, in their final message, they proudly proclaimed themselves “the first victims of American fascism.”

And that’s what’s missing from this film – any honest exploration of why the Rosenbergs kept silent, when admitting the truth would have spared their lives.

Those who know little about the case may well come away agreeing with Ivy Meeropol that “because of the position my grandparents took, we get to live a life in which we’re proud.” But the truth is that this tragic destruction of a young family was self-inflicted.

Eric Fettmann is an op-ed columnist and editorial writer for The New York Post.